Adaptation in Baltic Sea Region

Impacts & Vulnerabilities

The Baltic Sea Region (BSR) with its huge geographical extent covers two climatic zones: while a humid, sub-polar climate predominates in the north and northeast, the south and southwest show an oceanic, temperate climate. Global climate models project the warming of the BSR to be higher than the global mean warming will be. The climatic variety will most likely be increased. The region's high vulnerability to climate change is presented further below for four sectors: tourism, biodiversity, food production, and infrastructure.

Studies project a rise in temperature for all seasons for all parts of the BSR but with differences between seasons and regions. The increase is expected to be higher in winter (up to 4-6°C in the 21st century in the northern parts) than in summer. For some parts of the northern Baltic Sea, it might be even higher than 6°C. The mean annual temperature for the whole Baltic Sea basin is expected to increase by 3-5°C during this century. One severe consequence of the rising temperature is its effect on the Baltic Sea's salinity. As a result, the river runoffs are expected to increase which might cause a future decrease in both surface and bottom salinity.

Changes in precipitation:

The overall precipitation in the Baltic Sea basin is also expected to increase. The gain of rainfall will be largest in the northern parts of the region and occur mainly in winter. During the 20th century, a total increase of 10-50 mm per year was observed in some regions, while other regions became slightly drier. This trend is projected to continue yet with uneven seasonal and spatial distributions. While in the northern parts of the Baltic Sea basin the winter precipitation might increase by about 25-75 % until the end of the 21st century, the summer precipitation will alternate between -5 and 35 %. In the southern parts it is expected, that precipitation increases from 20 to 70 % in winter time and decreases up to 45 % in summer. Flood events become more likely, especially in the southern parts of the Baltic Sea during wintertime.

Changes in sea-ice conditions:

All models and scenarios used show drastic decreases in ice cover on the Baltic Sea for the next century, representing shorter ice seasons with decreased ice extent. Over the past century, the length of the ice season has already decreased by 14-44 days. It is expected that it will decrease further during the 21st century by up to 2-3 months in the central parts of the Baltic Sea.

Sea level rise:

Considering the rise in global sea levels and the expansion of seawater due to higher temperatures, the probability and possible duration for storm tides grows.

Sectoral impacts and vulnerabilities

These changing climate conditions will influence a whole range of sectors. For the four key issue areas biodiversity, tourism, food production, and infrastructure the impacts of climate change are highlighted below (for more information and policies on the single sectors see EU Sector Policies).

Biodiversity:

Increasing temperatures, a higher amount of freshwater inflow into the Baltic Sea caused by growing precipitation, and reduced salinity will have a direct impact on nutrition cycles in the Baltic Sea. Salt loving species might be driven out of their habitat because many of them, such as herring and sprat, are not originally adapted to the brackish water in the Baltic Sea environment and live at the edge of their physiological tolerance range in terms of salinity. Simultaneously, warm water-adapted exotic species from southern sea areas might reach the Baltic Sea and establish themselves in the long-term. All in all, the changing composition and distribution of species in the Baltic Sea can endanger the fishing industry and the biological diversity.

In case of high waters, nutrients can be transported by the water from arable farmland or moor areas into the Baltic Sea, reinforcing its over-fertilization. Furthermore, as temperatures rise, the ability of the ocean to retain oxygen will also decrease. The resulting surplus of nutrition inputs will worsen the water quality and disturb the marine ecosystem. Under these conditions, seaweed is more likely to survive, while driving out other species, perceptible at massive increases in algal blooms in the Baltic Sea. Especially in areas with reduced water renewal, this can, for instance, lead to benthic deserts.

Beyond that, climatic changes might result in reduced submerged vegetation, more pelagic plankton production, and changes in growth and reproduction parameters for fauna and flora. For more information on the impacts on biodiversity and habitats read the Baltadapt Report No. 3 and EU sector policies: Biodiversity.

Tourism:

Changes in temperature, water quality, precipitation and extreme weather events as well as sea level rise result in several risks for touristic offers and infrastructure. The extended need for cooling, water shortage, flood damages on infrastructure and interrupted business opera­tions leads to additional costs for the tourism industry. The coastal and beach erosion and the loss of native coastal species and habitats can decrease the attractiveness of certain touristic regions and attractions. Cyanobacteria bloom (blue-green algae bloom) caused by higher temperatures and over-fertilization in the Baltic Sea may affect beach tourism.

At the same time, the touristic sector in the BSR might profit from longer seasons and less rainfall in summer. For more information on the impacts of climate change on tourism see, for example, the outputs of the BaltCICA project and the Baltadapt Report No. 6.

Food production:

Agriculture is affected by climate change in terms of more extreme weather events, warmer average temperature, increased nutrient leach and increased precipitation. As far as the agricultural sector in the BSR is concerned, climate change determines the risks of depriva­tion of crop and livestock, occurrence of diseases and pests, and decrease in crop yields (e.g. in Lithuania and Poland). Flood events could damage buildings and infrastructures, as well as the water quality of the ground water if they reach the inland, which will also have severe impacts on agriculture.

However, climate change is also expected to disclose new possibilities for agriculture in the BSR. Crop and vegetable yields (e.g. in Estonia and Latvia) might increase, the growing season might extend and suitable crop varieties and areas for crop cultivation might expand. For more information, see EU sector policies: Agriculture & Forestry.

The fisheries are particularly endangered by a substantial increase of seawater temperature, changes in salinity, and changes in oxygen concentration and ocean acidification. The sector will most likely have to deal with changes in the distribution of species and the productivity of fish stocks. For more information on the impacts on fish stocks and fisheries, read the Baltadapt Report No. 4.

Infrastructure:

Climate change will influence the BSR infrastructure in terms of rising temperatures, decreasing sea ice cover, sea level rise, changing precipitation, changes in storm patterns, variability of weather, weather extremes, and wind waves. The changes might cause damage to infrastructure constructions, coastal protection, and cause difficulties for manoeuvring ships. However, these projected changes also hold new chances for the region. Mainly due to the decrease in sea ice cover, shipping could get easier and shipping seasons could be elongated. For more information on the impacts on infrastructure, read the Baltadapt Report No. 5 or visit EU sector policies: Infrastructure.

Uncertainty

The relative uncertainty of model simulation results on warming for the BSR is higher than on global warming due to the range of projections. For example, projections of warming from the late 20th century to the late 21st century for the northern part of the Baltic Sea range from 1°C in summer to more than 6°C in winter; the uncertainty for precipitation changes is even larger.

Models do not resolve small-scale variations of changes and micro-climatic conditions that are caused by regional topography and land cover. A more geographically detailed assess­ment and the use of statistical or dynamical downscaling methods is required. In addition, gaining knowledge, a continuing scientific process, and improvements in models will deliver updated and new projections.

However, decision-makers in adaptation planning have to deal with uncertainty. The uncertainty guidance helps them to factor uncertainty into adaptation decision-making and communicate it.